A team of researchers led by the psychologists and neuroscientists Prof. Markus Heinrichs and Dr. Bernadette von Dawans at the University of Freiburg, Germany, examined in a study how men react in stressful situations - and have refuted a nearly 100-year-old doctrine with their results. According to this doctrine, humans and most animal species show the "fight-or-flight" response to stress. Only since the late 1990s have some scientists begun to argue that women show an alternate "tend-and-befriend" response to stress - in other words, a protective ("tend") and friendship-offering ("befriend") reaction. Men, in contrast, were still assumed to become aggressive under stress. Von Dawans refuted this assumption, saying: "Apparently men also show social approach behavior as a direct consequence of stress."